# 19. oops concepts

 OOPS, Concepts:

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1. Data hiding

2. Data abstraction

3. Polymorphism

    3.1. Overloading

    3.2. Overriding

4. Encapsulation

    4.1 Tightly Encapsulation

5. IS-A Relationship

6. HAS-A Relationship (Composition/ aggregation)

7. Coupling

8. Cohesion

1. Data hiding:

 Our internal data should no go out directly

after validation only, If the user is valid/ authorized then only they can access the data is a mechanism called data hiding

data hiding means we are providing some security to the data

In java how we can implement data hiding?

By using a concept called private modifier

2. data abstraction:

By hiding internal implementations, just highlight a set of business methods/ services called data abstraction.

realtime example:

ATM

a lot of services ---> 

case1: we are seeing only services(highlight)

case2: we don't see business implementations(hiding)

Any application only services are showing

We can implement data abstraction using abstracts and interfaces.

4. Encapsulation:

Encapsulation is the process of wrapping the data into a container

Ex: Water bottle is a container we are wrapping water

In java where we are going to wrap our data inside a container is called class

Every java class is the best example of encapsulation

Tightly encapsulation:

A class is said to be a tightly encapsulation class if and only if all the variables in that class should be of type private and it doesn't care about methods.

the methods can be anything